Sandbox vectors

Let’s define some vectors which can be used for demonstrations:

manyNumbers <- sample( 1:1000, 20 )
manyNumbers
 [1] 294 235 993 247 677 602 201 757 258  21 261 953 448 323 965 357 772 381 383 860
manyNumbersWithNA <- sample( c( NA, NA, NA, manyNumbers ) )
manyNumbersWithNA
 [1] 383 201 357  21 247 235 448 953 261 772 757 965 323 677 294  NA  NA 860 993  NA 381 258 602
duplicatedNumbers <- sample( 1:5, 10, replace = TRUE )
duplicatedNumbers
 [1] 2 5 4 4 3 3 4 2 3 5
letters
 [1] "a" "b" "c" "d" "e" "f" "g" "h" "i" "j" "k" "l" "m" "n" "o" "p" "q" "r" "s" "t" "u" "v" "w" "x" "y" "z"
LETTERS
 [1] "A" "B" "C" "D" "E" "F" "G" "H" "I" "J" "K" "L" "M" "N" "O" "P" "Q" "R" "S" "T" "U" "V" "W" "X" "Y" "Z"
mixedLetters <- c( sample( letters, 5 ), sample( LETTERS, 5 ) )
mixedLetters
 [1] "x" "h" "e" "v" "i" "Q" "C" "V" "M" "P"

Are all/any elements TRUE

  • Input: logical vector
  • Output: single logical value
  • Task: try, understand what happens when you use manyNumbersWithNA instead of manyNumbers.
all( manyNumbers <= 1000 )
[1] TRUE
all( manyNumbers <= 500 )
[1] FALSE
any( manyNumbers > 1000 )
[1] FALSE
any( manyNumbers > 500 )
[1] TRUE
all( !is.na( manyNumbers ) )
[1] TRUE
any( is.na( manyNumbers ) )
[1] FALSE

Which elements are TRUE

Input: logical vector Output: vector of numbers (positions)

which( manyNumbers > 900 )
[1]  3 12 15
which( manyNumbersWithNA > 900 )
[1]  8 12 19
which( is.na( manyNumbersWithNA ) )
[1] 16 17 20

Filtering vector elements

  • Input: any vector and filtering condition
  • Output: elements of the input vector
  • Note: several ways to get the same effect
manyNumbers[ manyNumbers > 900 ] # indexing by logical vector
[1] 993 953 965
manyNumbers[ which( manyNumbers > 900 ) ] # indexing by positions
[1] 993 953 965
somePositions <- which( manyNumbers > 900 )
manyNumbers[ somePositions ]
[1] 993 953 965

Are some elements among other elements

  • Input: two vectors
  • Output: a logical vector corresponding to the first input vector
"A" %in% LETTERS
[1] TRUE
c( "X", "Y", "Z" ) %in% LETTERS
[1] TRUE TRUE TRUE
all( c( "X", "Y", "Z" ) %in% LETTERS )
[1] TRUE
all( mixedLetters %in% LETTERS )
[1] FALSE
any( mixedLetters %in% LETTERS )
[1] TRUE
mixedLetters[ mixedLetters %in% LETTERS ]
[1] "Q" "C" "V" "M" "P"
mixedLetters[ !( mixedLetters %in% LETTERS ) ]
[1] "x" "h" "e" "v" "i"
manyNumbers %in% 300:600
 [1] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE  TRUE  TRUE FALSE  TRUE FALSE
[18]  TRUE  TRUE FALSE
which( manyNumbers %in% 300:600 )
[1] 13 14 16 18 19
sum( manyNumbers %in% 300:600 )
[1] 5

Pick one of two (three) depending on condition

  • Input: a logical vector and two vectors additional vectors (for TRUE, for FALSE)
  • Output: elements of the additional vectors
  • Note: it can take care of NAs
if_else( manyNumbersWithNA >= 500, "large", "small" )
 [1] "small" "small" "small" "small" "small" "small" "small" "large" "small" "large" "large" "large" "small"
[14] "large" "small" NA      NA      "large" "large" NA      "small" "small" "large"
if_else( manyNumbersWithNA >= 500, "large", "small", "UNKNOWN" )
 [1] "small"   "small"   "small"   "small"   "small"   "small"   "small"   "large"   "small"   "large"  
[11] "large"   "large"   "small"   "large"   "small"   "UNKNOWN" "UNKNOWN" "large"   "large"   "UNKNOWN"
[21] "small"   "small"   "large"  
# here integer 0L is needed instead of real 0.0 
# manyNumbersWithNA contains integer numbers and the method complains
if_else( manyNumbersWithNA >= 500, manyNumbersWithNA, 0L ) 
 [1]   0   0   0   0   0   0   0 953   0 772 757 965   0 677   0  NA  NA 860 993  NA   0   0 602

Duplicates and unique elements

  • Input: a vector
unique( duplicatedNumbers )
[1] 2 5 4 3
unique( c( NA, duplicatedNumbers, NA ) )
[1] NA  2  5  4  3
duplicated( duplicatedNumbers )
 [1] FALSE FALSE FALSE  TRUE FALSE  TRUE  TRUE  TRUE  TRUE  TRUE

Positions of max/min elements

which.max( manyNumbersWithNA )
[1] 19
manyNumbersWithNA[ which.max( manyNumbersWithNA ) ]
[1] 993
which.min( manyNumbersWithNA )
[1] 4
manyNumbersWithNA[ which.min( manyNumbersWithNA ) ]
[1] 21
range( manyNumbersWithNA, na.rm = TRUE )
[1]  21 993

Sorting/ordering of vectors

manyNumbersWithNA
 [1] 383 201 357  21 247 235 448 953 261 772 757 965 323 677 294  NA  NA 860 993  NA 381 258 602
sort( manyNumbersWithNA )
 [1]  21 201 235 247 258 261 294 323 357 381 383 448 602 677 757 772 860 953 965 993
sort( manyNumbersWithNA, na.last = TRUE )
 [1]  21 201 235 247 258 261 294 323 357 381 383 448 602 677 757 772 860 953 965 993  NA  NA  NA
sort( manyNumbersWithNA, na.last = TRUE, decreasing = TRUE )
 [1] 993 965 953 860 772 757 677 602 448 383 381 357 323 294 261 258 247 235 201  21  NA  NA  NA
manyNumbersWithNA[1:5]
[1] 383 201 357  21 247
order( manyNumbersWithNA[1:5] )
[1] 4 2 5 3 1
rank( manyNumbersWithNA[1:5] )
[1] 5 2 4 1 3
sort( mixedLetters )
 [1] "C" "e" "h" "i" "M" "P" "Q" "v" "V" "x"

Ranking of vectors

manyDuplicates <- sample( 10:15, 10, replace = TRUE )
rank( manyDuplicates )
 [1] 7.5 5.5 2.5 9.5 2.5 2.5 2.5 5.5 9.5 7.5
rank( manyDuplicates, ties.method = "min" )
 [1] 7 5 1 9 1 1 1 5 9 7
rank( manyDuplicates, ties.method = "random" )
 [1]  8  5  4 10  3  2  1  6  9  7

Rounding numbers

v <- c( -1, -0.5, 0, 0.5, 1, rnorm( 10 ) )
v
 [1] -1.0000000 -0.5000000  0.0000000  0.5000000  1.0000000  0.2914521  0.6181840  1.2862645  1.0016778
[10] -0.9835793 -0.4566866  0.4675238  1.5351790 -0.4802953  1.3814644
round( v, 0 )
 [1] -1  0  0  0  1  0  1  1  1 -1  0  0  2  0  1
round( v, 1 )
 [1] -1.0 -0.5  0.0  0.5  1.0  0.3  0.6  1.3  1.0 -1.0 -0.5  0.5  1.5 -0.5  1.4
round( v, 2 )
 [1] -1.00 -0.50  0.00  0.50  1.00  0.29  0.62  1.29  1.00 -0.98 -0.46  0.47  1.54 -0.48  1.38
floor( v )
 [1] -1 -1  0  0  1  0  0  1  1 -1 -1  0  1 -1  1
ceiling( v )
 [1] -1  0  0  1  1  1  1  2  2  0  0  1  2  0  2

Naming vector elements

heights <- c( Amy = 166, Eve = 170, Bob = 177 )
heights
Amy Eve Bob 
166 170 177 
names( heights )
[1] "Amy" "Eve" "Bob"
names( heights ) <- c( "AMY", "EVE", "BOB" )
heights
AMY EVE BOB 
166 170 177 
heights[[ "EVE" ]]
[1] 170

Generating grids

expand_grid( x = c( 1:3, NA ), y = c( "a", "b" ) )
# A tibble: 8 x 2
      x y    
  <int> <chr>
1     1 a    
2     1 b    
3     2 a    
4     2 b    
5     3 a    
6     3 b    
7    NA a    
8    NA b    

Generating combinations

combn( c( "a", "b", "c", "d", "e" ), m = 2, simplify = TRUE )
     [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10]
[1,] "a"  "a"  "a"  "a"  "b"  "b"  "b"  "c"  "c"  "d"  
[2,] "b"  "c"  "d"  "e"  "c"  "d"  "e"  "d"  "e"  "e"  
combn( c( "a", "b", "c", "d", "e" ), m = 3, simplify = TRUE )
     [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10]
[1,] "a"  "a"  "a"  "a"  "a"  "a"  "b"  "b"  "b"  "c"  
[2,] "b"  "b"  "b"  "c"  "c"  "d"  "c"  "c"  "d"  "d"  
[3,] "c"  "d"  "e"  "d"  "e"  "e"  "d"  "e"  "e"  "e"  


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